A party has one proven location (5)
I believe the answer is:
alibi
'proven location' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'a party has one' is the wordplay.
'party' becomes 'lib' (abbreviation for Liberal, uk political party).
'has' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'a'+'lib'+'i'='ALIBI'
Can you help me to learn more?
(Other definitions for alibi that I've seen before include "Suspect's excuse" , "Story confirming innocence" , "I bail (anag.)" , "Timely excuse" , "Legal excuse" .)